The data consists of carbon, micro and macro nutrient concentrations in fine roots (<2mm diameter) in old growth forests in Central Amazon. Fine roots younger than three months were sampled using the ingrowth core technique in a large-scale nutrient fertilisation experiment. Carbon and nutrient concentrations refer to year one of fertilisation, bulking samples from November 2017 to August 2018. Concentrations are given as a mean of the community per plot in year 1, where five points inside each plot were sampled in the 0-10 cm and 10-30 cm soil layers. The dataset depicts the concentrations of iron, zinc, manganese, calcium, magnesium, potassium, phosphorus, nitrogen and carbon in fine roots in two different soil depths. Samples were collected at the AFEX project area in Manaus, Brazil at the Biological Dynamics of Forest Fragments Project (BDFFP/ INPA). The study was funded by NERC, BDFFP (logistical support) and Brazilian government (student scholarship). Full details about this dataset can be found at https://doi.org/10.5285/ba190356-1731-4558-be7a-3fedc570663a